This invention relates generally to seat and back support cushions and is more particularly directed to improvements in seating support cushions such as those adapted for use by a non-ambulatory, handicapped person.
Those who are non-ambulatory are restricted to either lying down or sitting for extended periods of time. Bony protuberances give rise to areas of excessive pressure restricting blood flow to the surrounding tissue. In order to avoid such problems, the person must be frequently moved in those areas to which blood circulation has been restricted and massaged in attempting to prevent the formation of an ulcer.
In addressing this potential problem for the bed-ridden as well as for those restricted to a wheel chair, attempts have been made to limit localized pressure and to distribute this pressure over greater areas of the body. One approach makes use of water-filled bladders. In the area of seating, liquid filled plastic bags have been used to reduce pressure on the ischials and coccyx. Because of the limited compressibility of the liquid used in the flexible plastic bag, this approach has not eliminated formation of pressure sores for those who remain in the seated position for extended periods. In order to increase the compressibility, gels having a variety of compositions have been incorporated in the plastic bag. These gels are typically comprised of a stable, chemically inert material which freely flows within the plastic bag. Unfortunately, even the gels used offer only limited compressibility and internal displacement and have not been particularly effective in improving the comfort and health of the wheel chair-ridden.
In order to provide for complete support, it is necessary to displace a weight of liquid equal to the weight of the body being supported. As a result, liquid-type systems capable of eliminating pressure sores are necessarily very heavy, bulky and difficult to utilize in a bed much less in a wheel chair. When the weight of the liquid displaced is less than that of the body weight of the user, the user will be exposed to increased pressures.
Liquid systems rely on a water-tight envelope and are thus subject to inadvertent punctures and/or leaks with a resulting loss of support. Gas (air) filled bags have also been used, but they too are subject to puncture and leakage. These fluid filled systems must be also be capable of compensating for temperature variations, pressure variations and the weight of the user.
These prior art fluid filled cushions also do not lend to the stability of the user and frequently create a fear of falling from the chair. For example, when one leans to one side of the chair, or shifts his weight in one direction, the fluid moves away from the lower side and into the higher side of the cushion, exaggerating the tendency to lean. This results not only in a person leaning more on a fluid filled cushion than on a solid cushion, but creates a feeling of instability and a fear of leaning too far to one side because of the resulting instability. This sense of instability inhibits the user's ability to maneuver the wheel chair and thus further restricts his or her self-reliance and freedom. Moreover, fluid filled bags are incapable of providing any lateral support which is frequently essential for those suffering from a spinal deformity or injury.
The present invention overcomes the aforementioned limitations by providing a contoured support cushion for either back or seat support having a compressible interior of a first type of foam and a flexible cover disposed thereover. The cushion further includes an insert of a second type of softer foam disposed within the first foam material to accommodate areas of support subject to high pressure. The cushion also includes a rigid base integrated with the foam interior for improved support and to facilitate mounting of the cushion to a support base as well as lateral reinforcement disposed within and integral with the foam interior of the cushion.